Re: low power out on HF


Jamie WW3S <ww3s@...>
 

well, got the final verdict on my 7000.....Matt from SAR in Michigan called today, turns out it was NOT the finals NOR the driver board.....apparently a diode that biases the finals went bad, Matt said he never saw that one before.....again, very prompt and courteous service from Matt in SAR Technical in Michigan, he just received my radio Friday, and called me about 10 am this morning !!!!


------ Original Message ------
From: "Paul Hansen" <pwhansen@...>
Sent: 1/20/2021 6:38:08 AM
Subject: Re: [ic7000] low power out on HF

Those are metal shields and there isn’t any heat sink compound on them. The compound is on the bottom of the transistors. 7 volts is way too high and nearly zero is way too low. Sounds like both of them are shot. Base on the amount of damage you are seeing, make sure the current sensing resistors are good. Usually, a visual inspection is all you need. Don’t forget to set the bias on each transistor when you replace them.

 

Thank You

 

Paul W. Hansen, W6XA

Amateur Radio Service

2134 Carthage Road

Tucker, GA 30084

(864) 222-3539

www.amateurradioservice.com

 

From: ic7000@groups.io [mailto:ic7000@groups.io] On Behalf Of Jamie WW3S
Sent: Tuesday, January 19, 2021 13:14
To: ic7000@groups.io
Subject: Re: [ic7000] low power out on HF

 

On TX, I get almost 7 volts on 1 final.....less than half a volt on the other.....looks like that area got very hot at one time....should there be heat sink compound between the metal plate on top of the finals and the case? The VHF/UHF finals all have "springs" on them to contact the case, not so on the hf finals ?

 

------ Original Message ------

From: "Paul Hansen" <pwhansen@...>

Sent: 1/19/2021 8:26:21 AM

Subject: Re: [ic7000] low power out on HF

 

25 watts kind of indicates one of the PA transistors has failed. Measure the gate voltage in TX. It should be anywhere between 3.5 and 4.5 volts. It should also be zero in RX.

 

Thank You

 

Paul W. Hansen, W6XA

Amateur Radio Service

2134 Carthage Road

Tucker, GA 30084

(864) 222-3539

www.amateurradioservice.com

 

From: ic7000@groups.io [mailto:ic7000@groups.io] On Behalf Of Jamie WW3S
Sent: Monday, January 18, 2021 21:49
To: ic7000@groups.io
Subject: [ic7000] low power out on HF

 

Only getting about 25 watts out or so on HF, VHF/UHF is fine, full power.....Its NOT the power cord, I've tried a couple different ones, same result, and those cords work fine with my 7300, I had a problem with the 7000 before, actually no power out on HF and SARS in Michigan, replaced maybe the driver transistor, is it common for this part to go bad? Any thing to watch out for to prevent it from happening in the future. 

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